1. Field of the Invention
The present invention is a power controller and a power management control method related to a power supply, particularly a power controller and a control method for providing numerous ways to protect the power supply.
2. Description of the Prior Art
A power supply is an electronic device used to convert power from batteries or AC mains into specific rating to power electronic products. The power supply is required by most electronic products. Among different kinds of power supplies, switching power supply is very popular in power supply industry for possessing superior conversion efficiency and small device size.
FIG. 1 is a block diagram illustrating a prior art switching power supply utilizing flyback topology. A bridge rectifier 20 substantially rectifies power from AC mains into DC input voltage VIN at an input power node IN. A primary winding PRM of a transformer stores energy when a power switch 34 is turned on; a secondary winding SEC and an auxiliary winding AUX of the transformer release energy when the power switch 34 is turned off. The secondary winding SEC delivers power to a load 24 and builds up an output voltage VOUT at an output node OUT. Similarly, power is delivered to a power controller 26 and an operation voltage VCC is built up at an operation power source node VCC. A feedback circuit 30 including a photo coupler, an LT431, and so forth, generates a feedback signal VFB at a feedback node FB of a compensation capacitor 32 according to an output voltage VOUT. The power controller 26 controls power conversion of the power supply according to the feedback signal VFB. A current detection signal VCS at a current detection node CS is substantially corresponding to a current IPRM flowing through the primary winding PRM and the power switch 34 via a first and a second resistor 38, 36.
The switching power supply of FIG. 1 is usually coupled to AC mains all the time thus many protection methods are required to prevent dangerous situation resulting from fault conditions. Common protection methods include over voltage protection OVP, over current protection OCP, over load protection OLP, and so forth.